Diagnostic breather dryer

ABSTRACT

A breather including desiccant for humidity control includes an electronic end of life detection system. A temperature sensor and humidity sensor provide a temperature and humidity of the desiccant to a controller. The controller determines the relative humidity of the desiccant. The controller determines that the desiccant, and thus breather, has reached its end of life (i.e., end of useful life) when the relative humidity reaches a predetermined relative humidity (e.g., 40%). Optionally, a pressure sensor provides a pressure of the reservoir to the controller. The controller determines a fault condition or end of life condition of the breather when the pressure exceeds a predetermined pressure.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application claims priority to and hereby incorporates byreference in its entirety U.S. Provisional Patent Application Ser. No.61/709,360 filed Oct. 4, 2012, entitled “BREATHER DRYER WITH INDICATOR.”

A portion of the disclosure of this patent document contains materialthat is subject to copyright protection. The copyright owner has noobjection to the reproduction of the patent document or the patentdisclosure, as it appears in the U.S. Patent and Trademark Office patentfile or records, but otherwise reserves all copyright rights whatsoever.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

REFERENCE TO SEQUENCE LISTING OR COMPUTER PROGRAM LISTING APPENDIX

Not Applicable

BACKGROUND OF THE INVENTION

The present invention relates generally to breathers for liquidreservoirs. More particularly, the present invention relates to humiditycontrolling breathers for liquid reservoirs.

Breathers allow for expansion of liquids and gases (e.g., air) in liquid(e.g., lubricant) reservoirs while preventing contamination of theliquid. For liquid reservoirs such as engine crank cases and lubricantstorage reservoirs, water vapor and dust particles in the air can bepulled into the liquid by the expansion and contraction action of theair and liquid in the reservoir with changes in temperature orbarometric pressure of the surrounding environment and the contents ofthe reservoir (i.e., fluid level changes in the reservoir). Currently,breathers are replaced on a schedule, whether the breathers are at theend of their useful life or not because it is difficult to tell when abreather has reached the end of its useful life. Alternatively,breathers utilize color changing desiccants to indicate when thebreather has reached the end of its useful life and needs replacement.The color changing desiccants require transparent breather housingswhich are generally weaker than opaque breather housings, presentchemical incompatibility issues, and the chemicals used to change colormay be considered toxic under some guidelines. Further, the color changemay be faint, difficult to see depending on the location and environmentof the reservoir and breather, and therefore difficult to interpret. Forexample, breather dryers (e.g., desiccant breathers) are commonlymounted on lubricating fluid reservoirs in large format wind turbines.The nacelles in these turbines are typically cramped and include manypoorly lit, hard to reach areas near lubrication reservoirs wherebreathers are located. Visibility of the breather and any color changeis therefore difficult to see. Additionally, the nacelle may typicallyonly be accessed when the wind turbine is shut down (i.e., stopped andnot generating power).

BRIEF SUMMARY OF THE INVENTION

Aspects of the present invention provide a breather with desiccant andan electronic end of life detection system. A temperature sensor andhumidity sensor provide a temperature and humidity of the desiccant to acontroller. The controller determines the relative humidity of thedesiccant, and determines that the desiccant, and thus breather, hasreached its end of life (i.e., end of useful life) when the relativehumidity reaches a predetermined relative humidity (e.g., 40%).

In one aspect, a breather for a reservoir includes a housing, a firstopening in the housing, a second opening in the housing, a desiccant,and a humidity sensor. The first opening in the housing is configured tobe in fluid communication with air outside the reservoir. The secondopening in the housing is configured to be in fluid communication withair inside the reservoir. The desiccant is positioned within the housingsuch that air passing through the breather from the outside to theinside of the reservoir of the reservoir must pass through thedesiccant. The humidity sensor is positioned within the housing. Thehumidity sensor is operable to provide a humidity signal indicative ofthe humidity level adjacent the humidity sensor. In one embodiment, thebreather further includes a controller electrically connected to thehumidity sensor. The controller is operable to determine an end of lifecondition of the breather as a function of the humidity signal from thehumidity sensor.

In another aspect, a method of determining an end of life condition of abreather includes providing a breather operable to attach to areservoir. The breather includes a housing, a first opening in thehousing, a second opening in the housing, a desiccant, and a humiditysensor. The first opening in the housing is configured to be in fluidcommunication with air outside of the reservoir. The second opening inthe housing is configured to be in fluid communication with air insideof the reservoir. The desiccant is positioned within the housing suchthat air passing through the breather from the outside to the inside ofthe reservoir must pass through the desiccant. The humidity sensor ispositioned within the housing. The emitted sensor provides a humiditysignal indicative of a humidity level adjacent the humidity sensor. Thehumidity signals received at a controller associated with the breatherand electrically connected to the humidity sensor. The controllerdetermines the end of life condition as a function of the humiditysignal received at the controller.

In another aspect, the breather for a reservoir includes a housing, afirst opening in the housing, a second opening in the housing, adesiccant, a first humidity sensor, a second humidity sensor, and acontroller. The first opening in the housing is configured to be influid communication with air outside of the reservoir. The secondopening in the housing is configured to be in fluid communication withair inside of the reservoir. The desiccant is positioned within thehousing such that air passing through the breather from the outside tothe inside of the reservoir must pass through the desiccant. The firsthumidity sensor is positioned within the housing and is operable toprovide a first humidity signal indicative of a first humidity leveladjacent the first humidity sensor. The first humidity sensor issubstantially surrounded by the desiccant. The second humidity sensor ispositioned within the housing and is operable to provide a secondhumidity signal indicative of a second humidity level adjacent thesecond humidity sensor. The second humidity sensor is positioned withinthe housing such that air passing through the breather from the insideof the reservoir to the desiccant must pass by the second humiditysensor. The controller is electrically connected to the first humiditysensor and the second humidity sensor. The controller is operable todetermine an end-of-life condition of the breather as a function of thefirst humidity signal received from the first humidity sensor and thesecond humidity signal received from the second humidity sensor.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a side cutaway view of a breather having a humidity sensor.

FIG. 2 is a flow chart of a method of determining an end of lifecondition of a breather.

FIG. 3 is a side cutaway view of a breather having dual humiditysensors.

DETAILED DESCRIPTION OF THE INVENTION

While the making and using of various embodiments of the presentinvention are discussed in detail below, it should be appreciated thatthe present invention provides many applicable inventive concepts thatcan be embodied in a wide variety of specific contexts. The specificembodiments discussed herein are merely illustrative of specific ways tomake and use the invention and do not delimit the scope of theinvention.

To facilitate the understanding of the embodiments described herein, anumber of terms are defined below. The terms defined herein havemeanings as commonly understood by a person of ordinary skill in theareas relevant to the present invention. Terms such as “a,” “an,” and“the” are not intended to refer to only a singular entity, but ratherinclude the general class of which a specific example may be used forillustration. The terminology herein is used to describe specificembodiments of the invention, but their usage does not delimit theinvention, except as set forth in the claims.

Referring to FIG. 1, a breather 100 for a reservoir includes a housing112, a first opening in the housing 114, a second opening in the housing116, a desiccant 118, a humidity sensor 102, and a controller 104. Thefirst opening in the housing 114 is configured to be in fluidcommunication with air outside of the reservoir. The second opening inthe housing is configured to be in fluid communication with air insidethe reservoir.

The desiccant 118 is positioned within the housing 112 such that airpassing through the breather 100 from the outside to the inside of thereservoir must pass through the desiccant 118. Air passing from theoutside to the inside of the reservoir may bypass the desiccant 118 orbe routed through the desiccant 118.

The humidity sensor 102 is positioned within the housing 112. Thehumidity sensor 102 is operable to provide a humidity signal indicativeof the humidity level adjacent the humidity sensor 102. In oneembodiment, the breather 100 further includes a temperature sensor 120associated with (e.g., positioned in or near) the housing 112. In oneembodiment, the humidity sensor 102 is integral with the temperaturesensor 120. The temperature sensor 120 is also electrically connected tothe controller 104, and the temperature sensor 120 is operable toprovide a temperature signal indicative of a temperature adjacent thetemperature sensor 120 to the controller 104. In one embodiment, thehousing 112 includes an adapter to locate the humidity sensor 102,pressure sensor 140, and/or temperature sensor 120 remote from a mainportion of the housing 112.

The controller 104 is electrically connected to the humidity sensor 102.The controller 104 may be local to the housing 112 or remote from thehousing 112. The controller 104 may be electrically connected to thehumidity sensor 102 via a wired or wireless communications link. Thecommunications link may be analog or digital. The controller 104 isoperable to determine an end of life condition of the breather 100 as afunction of the humidity signal received from the humidity sensor 102.In one embodiment, the controller 104 is operable to determine the endof life condition as a function of the humidity signal received from thehumidity sensor 102 and the temperature sensor received from thetemperature sensor 120. The controller 104 uses the temperature signaland the humidity signal to determine a relative humidity associated withthe desiccant 118. In actual usage, the relative humidity stabilizesafter initial installation of the breather 100 on the reservoir, and thebreather 100 reaches the end of its useful life (i.e., end of life) whenthe relative humidity reaches a predetermined maximum relative humidity.In one embodiment, the relative humidity may stabilize at approximately20 to 25% and increase generally linearly up to the maximum relativehumidity (i.e., the relative humidity indicating end of life or end ofuseful life of the breather 100) of approximately 40%. In oneembodiment, the controller 104 is operable to determine the end of lifecondition by determining an estimated time of life remaining or anestimated percentage of life remaining as a function of the determinedrelative humidity and a historical rate of change of the relativehumidity calculated by the controller based on previous relativehumidity calculations.

In one embodiment, the breather 100 further includes a display 130. Thedisplay 130 is electrically connected to the controller 104. The display130 may be local to the controller 104 or remote from the controller104. The electrical connection between the display 130 and thecontroller 104 may be wired or wireless, and may communicate data in ananalog or digital format. The controller 104 is operable to provide anend of life signal indicative of the end of life status (i.e., end oflife condition) determined by the controller 104. The display 130 isoperable to receive the end of life signal from the controller 104 anddisplay to an observer an indication of the end of life status of thebreather 100 as a function of the received end of life signal. The endof life signal is indicative of at least one of a relative humidityvalue, a percentage of life remaining, and an estimated remaining timeof life. The end of life status displayed by the display 130 includesthe at least one relative humidity value, percentage of life remaining,or estimated remaining time of life indicated by the end of life signalprovided by the controller 104.

In one embodiment, the breather 100 further includes a pressure sensor140. The pressure sensor 140 is positioned within the housing 112 suchthat air passing through the breather 100 from the inside of thereservoir to the desiccant 118 must pass by the pressure sensor 140. Thepressure sensor 140 is operable to provide a pressure signal indicativeof an air pressure adjacent the pressure sensor 140 to the controller104. The controller 104 is further configured to determine a fallcondition when the pressure signal indicates that the air pressureadjacent the presser sensor 140 is above a predetermined pressure limit.In operation, when this pressure is above the predetermined limit, itcan be inferred that the airflow requirements of the reservoir have notbeen properly matched to an appropriately sized breather (i.e., a largercapacity breather should be used with the given reservoir), the breather100 is improperly installed, or has reached particulate or humiditysaturation (i.e., end of life or end of useful life) and is no longereffective. In one embodiment, the pressure sensor 140 is a differentialpressure sensor comprising a first pressure sensor in fluidcommunication with the air inside the reservoir and a second pressuresensor in fluid communication with the air outside the reservoir. Inthis embodiment, when the differential pressure sensed by the pressuresensor 140 exceeds a predetermined limit, the controller 104 is operableto determine the fault condition and communicate the fault condition tothe display 130 for display to an observer.

In one embodiment, the housing 112 includes a rigid or semi-rigid body142 and a cap 146. The breather 100 has a foam bottom 160, a foam top162, a particulate filter bottom 164, a particulate filter top 166, anda filter ring 190. A space between the foam top 162 and cap 146 definesa breather headspace 170. The foam top 162 is between the desiccant 118and cap 146. The breather 100 includes a standpipe 110. The standpipe110 has a standpipe bottom end 106 and a stand standpipe top end 108.The standpipe bottom end 106 includes a threaded section 180 operable toengage corresponding threads of the reservoir. In one embodiment, asshown in FIG. 1, the humidity sensor 102 is substantially surrounded bythe desiccant 118. That is, the humidity sensor 102 is located withinthe desiccant 118. In another embodiment, the humidity sensor 102 islocated within the breather cap headspace 170 of the breather 100. Inone embodiment, the pressure sensor 140 is also included located withinthe breather cap headspace 170. In another embodiment, the humiditysensor 102 is located within the standpipe 110. It is contemplated thatthe humidity sensor 102 may be located within the desiccant 118,partially within desiccant 118 on the second opening 116 side of thedesiccant 118 such that air has to flow past the humidity sensor 102 asit passes between the desiccant 118 and the second opening 116, oroutside of the desiccant 118 on the second opening 116 side of thedesiccant 118 such that air has to flow past the humidity sensor 102 asit passes between the desiccant 118 and the second opening 116. It iscontemplated within the scope of the claims that the breather 100 mayinclude any number of first openings 114 and any number of secondopenings 116. In embodiment, the first opening(s) 114 includes a 2 way,pressure limited check valve. The check valve reduces exposure of thedesiccant 118 to the atmosphere to prolong the useful life of thedesiccant 118 and thus breather 100. The pressure limit prevents smallfluctuations in pressure in the reservoir from drawing air through thedesiccant 118 while allowing larger, less transient pressure changes todraw air through the desiccant 118 and maintain the proper pressure inthe reservoir (e.g., approximately atmospheric or environmentalpressure). In one embodiment, the check valve is limited at 0.2 psi ineither direction.

During out-breathing, as moisturized air from the reservoir headspaceenters the standpipe bottom side 106 and flows upward in to the breatherheadspace 170. The air then passes through the foam filter top 162 andparticulate filter 166 to remove the dust particles over 3 microns outof the air. The air then passes through the desiccant 118 where moisturegets absorbed or adsorbed from the air.

During in-breathing, breather 100 draws air from the surrounding spacein through the first opening 114. This air first comes through thebottom foam filter 160, then the bottom particulate filter 164 whereparticles over 3 microns are removed. The air then passes through thedesiccant 118 where moisture is absorbed or adsorbed by the desiccant118, and clean, dry air enters in to the top side of standpipe 108,where it can flow into the reservoir headspace.

In one embodiment, the initial installation of the breather 100 on thereservoir includes removing the breather 100 from packaging, attachingthe breather 102 threads of the reservoir corresponding to the threadedportion 180 of the standpipe 110, and providing power to the controller104. Following initial installation, as desiccant 118 absorbs or adsorbsmoisture from the reservoir headspace and relative humidity in thereservoir headspace and breather 100 decrease. In one embodiment, thecontroller 104 is configured to ignore the humidity signal from thehumidity sensor 102 until the humidity signal indicates that thehumidity level adjacent the humidity sensor 102 has decreased below apredetermined maximum humidity level. In one embodiment, thepredetermined maximum humidity level is a relative humidity level, andthe controller 104 determines that the humidity level adjacent thehumidity sensor 102 has decreased below the predetermined maximumhumidity level as a function of both the temperature signal provided bythe temperature sensor 120 and the humidity signal provided by thehumidity sensor 102. In another embodiment, the controller 104 isconfigured to ignore the humidity signal for a predetermined period oftime after initial installation of the breather 100 on the reservoir toallow the humidity adjacent the humidity sensor 102 to drop below thepredetermined maximum humidity level. As continuous in-breathing andout-breathing of the air continues, desiccant 118 gradually reaches itsfull saturation capacity and will no longer absorb or adsorb themoisture out of the air passing therethrough. This allows moisturizedair pass through and flow in and out of the tank headspace if thebreather 100 is not replaced.

Referring to FIG. 2, a method 200 of determining an end of lifecondition of the breather 100 begins at 202 when the controller 104receives power. At 204, the control delays program as a function of timeor a calculator relative humidity as described above to allow thehumidity inside the breather 100 to stabilize. In one embodiment, thecontroller 104 delays the start of the humidity sensor monitoring cyclefor a predetermined period of time to allow the humidity in thereservoir and desiccant 118 to stabilize following installation of thebreather 100 on the reservoir. It is contemplated within the scope ofthe claims that the delay may be more or less than 24 hours depending onthe intended environment of the breather 100 including the systemproperties (e.g., volume of reservoir, headspace of reservoir, number ofbreathers, etc.). At 206, the controller 104 reads the temperaturesensor 120 and the humidity sensor 102. At 208, the controller 104calculates the actual relative humidity in the breather 100 based on thedata read from the temperature sensor 120 and the humidity sensor 102.At 210, the controller 104 determines whether the relative humidity isgreater than 40%. If the controller determines that the relativehumidity is not greater than 40%, then the controller 104 provides therelative humidity to the display 130 (e.g., an LCD display) for displayto an observer and again samples the temperature sensor 120 and thehumidity sensor 102 at 206. If the controller 104 determines that therelative humidity is greater than 40% at 210, then the controller 104senses the relative humidity to the display 134 display to an observerat 214. At 214, the controller 104 may also set an alarm or provideadditional input to the display 130 indicating that the breather 100 hasreached the end of its useful life. The method ends at 216 when thecontroller 104 ceases to receive power.

It is contemplated that the breather 100 disclosed herein may be usedwith reservoirs containing lubricating oils, hydraulic fluids, andspecial chemicals to protect those contents from moisture andparticulate ingestion under virtually any condition in any application.It is also contemplated that the desiccant 118 may include Silica Gel(All Varieties); Activated Alumina; Molecular Sieve (All Varieties);Activated Carbon/Charcoal (All Varieties); Alumino Silcate gels:KC-Trockenperlen® N, KC-Trockenperlen® WS; Calcium Sulfate; ZR gel Grain(ZR,TI); Sodium Polyacrylate; Hygroscopic salts/deliquescent salts; andGlycols, or any combination thereof. In one embodiment, electroniccomponents (e.g., the controller 104 and display 130) are encapsulatedin moisture impermeable material (e.g., epoxy resin) to avoid particlecontamination and premature failure.

Referring to FIG. 3, in one embodiment, the breather 100 includes dualhumidity sensors. The humidity sensor 102 is a first humidity sensor 102positioned within the housing 112 and substantially surrounded by thedesiccant 118. The first humidity sensor 102 is operable to provide afirst humidity signal indicative of a first humidity level adjacent thefirst humidity sensor 102 to the controller 104.

A second humidity sensor 302 may be integral with the pressure sensor140 and position within the housing 112 such that air passing throughthe breather 100 from the inside of the reservoir to the desiccant 118and vice versa must pass by the second humidity sensor 302. The secondhumidity sensor 302 is operable to provide a second humidity signalindicative of a second humidity level adjacent the second humiditysensor to the controller 104. It is contemplated within the scope of theclaims that the second humidity sensor 302 may be located within athread adapter for adapting the threads of the threaded portion orsection 180 of the housing 112 to threads of a corresponding section ofthe reservoir. In such an embodiment, the housing 112 is considered toinclude the thread adapter.

The controller 104 is electrically connected to both the first humiditysensor 102 and the second humidity sensor 302. The controller isoperable to receive the first humidity signal from the first humiditysensor 102 and the second humidity signal from the second humiditysensor 302. The controller 104 is operable to determine an end of lifecondition of the breather 100 as a function of the first humidity signaland the second humidity signal. When the first humidity level indicatedby the first humidity signal is approximately equal to or greater thanthe second humidity level indicated by the second humidity signal, thecontroller 104 operates normally as described above to determine the endof life condition by determining the relative humidity associated withthe first humidity sensor 102.

In one embodiment, when the first humidity level indicated by the firsthumidity signal is less than the second humidity level indicated by thesecond humidity signal, the controller 104 can determine a faultcondition. The first humidity level being less than the second humiditylevel indicates that the reservoir has not dried completely (i.e., therelative humidity at the second humidity sensor 302 is still trendingdownward after initial installation of the breather 100 on thereservoir) or that moisture is getting into the reservoir in some way.In one embodiment, the controller 104 differentiates between initialinstallation and moisture penetration into the reservoir as a functionof the rate of decrease of the relative humidity at the second humiditysensor 302 and the time after initial installation (i.e. power up of thecontroller 104). That is, if the rate of decrease of the relativehumidity of the second humidity sensor 302 decreases without acorresponding increase in the humidity at the first humidity sensor 102,then the controller 104 determines that there is water intrusion intothe reservoir. In this embodiment, the controller 104 only determinesthe fault condition when the controller 104 determines that there iswater intrusion into the reservoir.

In one embodiment, the determined end of life condition is another faultcondition. The controller 104 determines a dewpoint as a function of thepressure signal from the pressure sensor 140 and the temperature signalfrom the temperature sensor 120. When the second humidity level adjacentthe second humidity sensor 302 indicates that the second humidity levelis greater than the dewpoint, the controller 104 determines the faultcondition. In one embodiment, the controller 104 is operable to transmitfault conditions (i.e., end-of-life conditions) to remote terminals ordisplays 130.

It will be understood by those of skill in the art that information andsignals may be represented using any of a variety of differenttechnologies and techniques (e.g., data, instructions, commands,information, signals, bits, symbols, and chips may be represented byvoltages, currents, electromagnetic waves, magnetic fields or particles,optical fields or particles, or any combination thereof). Likewise, thevarious illustrative logical blocks, modules, circuits, and algorithmsteps described herein may be implemented as electronic hardware,computer software, or combinations of both, depending on the applicationand functionality. Moreover, the various logical blocks, modules, andcircuits described herein may be implemented or performed with a generalpurpose processor (e.g., microprocessor, conventional processor,controller, microcontroller, state machine or combination of computingdevices), a digital signal processor (“DSP”), an application specificintegrated circuit (“ASIC”), a field programmable gate array (“FPGA”) orother programmable logic device, discrete gate or transistor logic,discrete hardware components, or any combination thereof designed toperform the functions described herein. Similarly, steps of a method orprocess described herein may be embodied directly in hardware, in asoftware module executed by a processor, or in a combination of the two.A software module may reside in RAM memory, flash memory, ROM memory,EPROM memory, EEPROM memory, registers, hard disk, a removable disk, aCD-ROM, or any other form of storage medium known in the art. Althoughembodiments of the present invention have been described in detail, itwill be understood by those skilled in the art that variousmodifications can be made therein without departing from the spirit andscope of the invention as set forth in the appended claims.

A controller, processor, computing device, client computing device orcomputer, such as described herein, includes at least one or moreprocessors or processing units and a system memory. The controller mayalso include at least some form of computer readable media. By way ofexample and not limitation, computer readable media may include computerstorage media and communication media. Computer readable storage mediamay include volatile and nonvolatile, removable and non-removable mediaimplemented in any method or technology that enables storage ofinformation, such as computer readable instructions, data structures,program modules, or other data. Communication media may embody computerreadable instructions, data structures, program modules, or other datain a modulated data signal such as a carrier wave or other transportmechanism and include any information delivery media. Those skilled inthe art should be familiar with the modulated data signal, which has oneor more of its characteristics set or changed in such a manner as toencode information in the signal. Combinations of any of the above arealso included within the scope of computer readable media. As usedherein, server is not intended to refer to a single computer orcomputing device. In implementation, a server will generally include anedge server, a plurality of data servers, a storage database (e.g., alarge scale RAID array), and various networking components. It iscontemplated that these devices or functions may also be implemented invirtual machines and spread across multiple physical computing devices.

This written description uses examples to disclose the invention andalso to enable any person skilled in the art to practice the invention,including making and using any devices or systems and performing anyincorporated methods. The patentable scope of the invention is definedby the claims, and may include other examples that occur to thoseskilled in the art. Such other examples are intended to be within thescope of the claims if they have structural elements that do not differfrom the literal language of the claims, or if they include equivalentstructural elements with insubstantial differences from the literallanguages of the claims.

It will be understood that the particular embodiments described hereinare shown by way of illustration and not as limitations of theinvention. The principal features of this invention may be employed invarious embodiments without departing from the scope of the invention.Those of ordinary skill in the art will recognize numerous equivalentsto the specific procedures described herein. Such equivalents areconsidered to be within the scope of this invention and are covered bythe claims.

All of the compositions and/or methods disclosed and claimed herein maybe made and/or executed without undue experimentation in light of thepresent disclosure. While the compositions and methods of this inventionhave been described in terms of the embodiments included herein, it willbe apparent to those of ordinary skill in the art that variations may beapplied to the compositions and/or methods and in the steps or in thesequence of steps of the method described herein without departing fromthe concept, spirit, and scope of the invention. All such similarsubstitutes and modifications apparent to those skilled in the art aredeemed to be within the spirit, scope, and concept of the invention asdefined by the appended claims.

Thus, although there have been described particular embodiments of thepresent invention of a new and useful DIAGNOSTIC BREATHER DRYER it isnot intended that such references be construed as limitations upon thescope of this invention except as set forth in the following claims.

What is claimed is:
 1. A breather for a reservoir, said breathercomprising: a housing; a first opening in the housing configured to bein fluid communication with air outside of the reservoir; a secondopening in the housing configured to be in fluid communication with airinside of the reservoir; desiccant positioned within the housing suchthat air passing through the breather from the outside to the inside ofthe reservoir must pass through the desiccant; and a humidity sensorpositioned within the housing, wherein the humidity sensor is operableto provide a humidity signal indicative of a humidity level adjacent thehumidity sensor.
 2. The breather of claim 1, said breather furthercomprising: a controller electrically connected to the humidity sensor,wherein the controller is operable to determine an end of life conditionof the breather as a function of the humidity signal from the humiditysensor.
 3. The breather of claim 2, wherein the housing comprises abreather cap headspace and the humidity sensor is positioned in thebreather cap headspace.
 4. The breather of claim 2, wherein the humiditysensor is substantially surrounded by the desiccant.
 5. The breather ofclaim 2, wherein the humidity level decreases after initial installationof the breather on the reservoir, and the controller is configured to atleast one of: ignore the humidity signal until the humidity signalindicates that the humidity level adjacent the humidity sensor hasdecreased below a predetermined maximum humidity level; or ignore thehumidity signal for a predetermined period of time after initialinstallation of the breather on the reservoir, wherein initialinstallation of the breather on the reservoir comprises providing powerto the controller.
 6. The breather of claim 2, further comprising adisplay electrically connected to the controller, wherein the display isoperable to receive an end of life signal from the controller anddisplay to an observer an indication of an end of life status of thebreather as a function of the received end of life signal.
 7. Thebreather of claim 2, further comprising a display electrically connectedto the controller, wherein the display is operable to receive an end oflife signal from the controller and display to an observer an indicationof an end of life status of the breather as a function of the receivedend of life signal, wherein the end of life signal is indicative of oneof a relative humidity value, a percentage of life remaining, and anestimated remaining time of life, and the displayed end of life statuscomprises the indicated one of the relative humidity value, thepercentage of life remaining, or the estimated remaining time of life.8. The breather of claim 2, further comprising a pressure sensorpositioned within the housing such that air passing through the breatherfrom the inside of the reservoir to the desiccant must pass by thepressure sensor, wherein: the pressure sensor is operable to provide apressure signal indicative of an air pressure adjacent the pressuresensor; and the controller is further configured to determine a faultcondition when the pressure signal indicates that the air pressureadjacent the pressure sensor is above a predetermined pressure limit. 9.The breather of claim 2, further comprising a temperature sensorelectrically connected to the controller, wherein: the temperaturesensor is operable to provide a temperature signal indicative of atemperature adjacent the temperature sensor; and the controller isfurther operable to determine the end of life condition of the breatheras a function of the humidity signal from the humidity sensor and thetemperature signal from the temperature sensor by calculating a relativehumidity associated with the desiccant as a function of the humiditysignal and the temperature signal.
 10. A method of determining an end oflife condition of a breather, said method comprising: providing abreather operable to attach to a reservoir, wherein the breathercomprises: a housing; a first opening in the housing configured to be influid communication with air outside of the reservoir; a second openingin the housing configured to be in fluid communication with air insideof the reservoir; desiccant positioned within the housing such that airpassing through the breather from the outside to the inside of thereservoir must pass through the desiccant; and a humidity sensorpositioned within the housing; providing, via the humidity sensor, ahumidity signal indicative of a humidity level adjacent the humiditysensor; and receiving the humidity signal at a controller associatedwith the breather and electrically connected to the humidity sensor;determining, via the controller, the end of life condition as a functionof the humidity signal received at the controller.
 11. The method ofclaim 10, wherein the housing of the breather comprises a breather capheadspace and the humidity sensor is positioned in the breather capheadspace.
 12. The method of claim 10, wherein the humidity sensor issubstantially surrounded by the desiccant.
 13. The method of claim 10,wherein the humidity level decreases after initial installation of thebreather on the reservoir, and the method further comprises at least oneof: ignoring, via the controller, the humidity signal received at thecontroller until the humidity signal indicates that the humidity leveladjacent the humidity sensor has decreased below a predetermined maximumhumidity level; or ignoring, via the controller, the humidity signalreceived at the controller for a predetermined period of time afterinitial installation of the breather on the reservoir, wherein initialinstallation of the breather on the reservoir comprises providing powerto the controller.
 14. The method of claim 10, further comprising:receiving an end of life signal from the controller at a displayelectrically connected to the controller, and displaying, via thedisplay, to an observer an indication of an end of life status of thebreather as a function of the received end of life signal.
 15. Themethod of claim 10, further comprising: receiving an end of life signalfrom the controller at a display electrically connected to thecontroller, and displaying, via the display, to an observer anindication of an end of life status of the breather as a function of thereceived end of life signal, wherein the end of life signal isindicative of one of a relative humidity value, a percentage of liferemaining, and an estimated remaining time of life, and the displayedend of life status comprises the indicated one of the relative humidityvalue, the percentage of life remaining, or the estimated remaining timeof life.
 16. The method of claim 10, wherein the breather furthercomprises a pressure sensor positioned within the housing such that airpassing through the breather from the inside of the reservoir to thedesiccant must pass by the pressure sensor, and wherein the methodfurther comprises: providing, via the pressure sensor, a pressure signalindicative of an air pressure adjacent the pressure sensor; andreceiving the provided pressure signal at the controller; anddetermining, via the controller, a fault condition when the pressuresignal indicates that the air pressure adjacent the pressure sensor isabove a predetermined pressure limit.
 17. The method of claim 10,wherein the breather further comprises a temperature sensor electricallyconnected to the controller, and the method further comprises:providing, via the temperature sensor, a temperature signal indicativeof a temperature adjacent the temperature sensor; receiving the providedtemperature signal at the controller; and determining, via thecontroller, the end of life condition of the breather as a function ofthe humidity signal from the humidity sensor and the temperature signalfrom the temperature sensor by calculating a relative humidityassociated with the desiccant as a function of the humidity signal andthe temperature signal.
 18. A breather for a reservoir, said breathercomprising: a housing; a first opening in the housing configured to bein fluid communication with air outside of the reservoir; a secondopening in the housing configured to be in fluid communication with airinside of the reservoir; desiccant positioned within the housing suchthat air passing through the breather from the outside to the inside ofthe reservoir must pass through the desiccant; a first humidity sensorpositioned within the housing, wherein the first humidity sensor isoperable to provide a first humidity signal indicative of a firsthumidity level adjacent the first humidity sensor and the first humiditysensor is substantially surrounded by the desiccant; a second humiditysensor positioned within the housing, wherein the second humidity sensoris operable to provide a second humidity signal indicative of a secondhumidity level adjacent the second humidity sensor and the secondhumidity sensor is positioned within the housing such that air passingthrough the breather from the inside of the reservoir to the desiccantmust pass by the second humidity sensor; and a controller electricallyconnected to the first humidity sensor and the second humidity sensor,wherein the controller is operable to determine an end of life conditionof the breather as a function of the first humidity signal received fromthe first humidity sensor and the second humidity signal received fromthe second humidity sensor.
 19. The breather of claim 18, wherein thecontroller is further operable to determine a fault condition when thefirst humidity signal indicates that the first humidity level adjacentthe first humidity sensor is less than the second humidity leveladjacent the second humidity sensor as indicated by the second humiditysensor.
 20. The breather of claim 18, further comprising: a pressuresensor positioned within the housing such that air passing through thebreather from the inside of the reservoir to the desiccant must pass bythe pressure sensor, wherein the pressure sensor is operable to providea pressure signal indicative of an air pressure adjacent the pressuresensor; and a temperature sensor electrically connected to thecontroller, wherein: the temperature sensor is operable to provide atemperature signal indicative of a temperature adjacent the temperaturesensor; and the controller is further operable to determine a dew pointas a function of the pressure signal, the temperature signal, anddetermine the fault condition when the second humidity signal indicatesthat the humidity in the reservoir is greater than the determined dewpoint.